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Biol 101 #2
| asexual reproduction | produces offspring that are genetic copies of the parent and identical to each other |
| sexual reproduction | creates a variety of offspring (genetically different) |
| why cell division is essential for prokaryotic and eukaryotic life | cell division is important for: development, growth, repair (in multicellular organisms), reproduction (in unicellular & multi cellular organisms) |
| binary fission (how daughter prokaryotic chromosomes) | the cell replicated its chromosome, the copies (daughter prokaryotic chromosomes) attach to the plasma membrane and being pulled apart as the cell elongates, the plasma membrane pinches inward, a cell wall, dividing the parent cell into two daughter cells |
| Binary fission | a simple, rapid form of asexual reproduction used by prokaryotes (like bacteria) and some single-celled eukaryotes, where a single parent cell replicates its DNA and splits into two identical daughter cells |
| prokaryotic chromosomes | Usually one circular DNA molecule, Located in cytoplasm. |
| eukaryotic chromosomes | Many chromosomes, Located in the nucleus, Each chromosome is one long DNA molecule, Visible only during cell division, Outside division, DNA exists as chromatin |
| phases of the cell cycle | interphase, mitotic phase |
| interphase | G1 (first gap) – cell grows S (DNA synthesis) – chromosomes duplicate G2 (second gap) |
| Mitotic Phase (M) | Mitosis (division of nucleus), Cytokinesis (division of cytoplasm) |
| stages of mitosis | Prophase, Prometaphase, Metaphase, Anaphase, telophase, cytokinesis |
| prophase | chromatin condenses into chromosomes, Mitotic spindle forms, centrosomes move |
| prometaphase | nuclear envelope breaks down, spindle fibers attach to kinetochores (proteins on centromere), chromosomes move toward center |
| metaphase | chromosomes align at cell equator |
| Anaphase | centromeres separate, sister chromatids become individual chromosomes, spindle fibers pull them to opposite poles |
| Telophase | chromosomes decondense, nuclear membranes reform, spindle disappears |
| cytokinesis | cytoplasm divides |
| cytokinesis (animal and plant cells) | Animals: cleavage furrow forms, contracting ring of microfilaments divides cell. Plants: vesicles form a cell plate, new cell wall forms between daughter cells. |
| how cell density and growth factors control cell division | density dependent inhibition: cells stop dividing when they bump into other cells, most animal cells divide only when stimulated by growth factors, growth factors bind to receptors, a control system regulated check points (G1, G2, M) |
| how cancerous cells | caused by mutations (chromosome breakage or DNA errors), cell cycle control system breaks down, cells divide uncontrollably, form tumors, lose specific functions of a normal cells. |
| how chromosomes are paired | Homologous chromosomes: carry genes for the same characteristics at the same locus. humans have 23 homologous pairs, in males X and Y are not fully homologous |
| somatic cells vs gametes | somatic cells: body cells (diploid). gametes: eggs & sperm (haploid). |
| Haploid vs diploid | Diploid: two sets of chromosomes. Haploid: one set of chromosomes |
| why sexual reproduction requires meiosis | meiosis reduces chromosome number from diploid to haploid, produces gametes, without meiosis, chromosome number would double each generation |
| mitosis and meiosis similarities | begin with diploid parent cells, DNA duplicated in interphase |
| mitosis and meiosis differences | Mitosis: produces 2 genetically identical diploid cells; used for growth, repair, asexual reproduction. Meiosis: produces 4 genetically unique haploid gametes; used for sexual reproduction; involves two divisions |
| stages of meiosis I and II | Meiosis I (Homologous chromosomes separate): Prophase I, Metaphase I, Anaphase I, Telophase I. Meiosis II (Sister chromatids separate): Prophase II, Metaphase II, Anaphase II, Telophase II |
| Meiosis I | homologous chromosomes sperate |
| prophase I | homologous chromosomes pair, crossing over occurs |
| metaphase I | homologous pairs align |
| anaphase I | homologous chromosomes separate |
| telophase I | nuclear membranes reform |
| Meiosis II | sister chromatids separate |
| prophase II | spindle attaches to sister chromatids |
| metaphase II | chromosomes align at equator |
| anaphase II | sister chromatids separate |
| telophase II | nuclear membranes reform, cytokinesis produces 4 haploid cells |
| how genetic variation is produced | independent orientation of chromosomes at metaphase I; crossing over during prophase I (exchange between non-sister chromatids); random fertilization of egg by sperm |
| independent orientation | random alignment of maternal and paternal homologous pairs along the metaphase plate |
| crossing over | the exchange of genetic material between homologous chromosomes during prophase I of meiosis |
| true breeding organisms | homozygous and produce offspring with the same traits when self-fertilized |
| hybrids | heterozygous organisms produced by crossing two different true breeding parents |
| P generation | the parental generation (grandparents) |
| F1 generation | the first filial generation (patents), produced from the P generation |
| F2 generation | produced by crossing F1 individuals (you and siblings) |
| Homozygous | having two identical alleles for a gene |
| Heterozygous | having two different alleles for a gene |
| Dominant allele | determines appearance when present |
| Recessive allele | has no noticeable effect when a dominant allele is present |
| Genotype | genetic makeup (allele combination) |
| Phenotype | observable traits |
| monohybrid cross | examines inheritance of a single gene |
| Punnett square | shows all possible allele combinations form gamete fusion |
| how Mendel’s law of segregation describes the inheritance of a single character | Mendel’s law of segregation states that the two alleles for a gene separate during gamete formation so each gamete carries only one allele, and offspring receive one allele from each parent. |
| Describe the genetic relationships between homologous chromosomes | Homologous chromosomes carry alleles for the same genes at the same loci but may have different alleles, and they separate during meiosis I. |
| Explain how Mendel’s law of independent assortment applies to a dihybrid cross | The law of independent assortment states that allele pairs segregate independently during gamete formation, producing a 9:3:3:1 phenotypic ratio in a dihybrid cross when genes are not linked. |
| Explain how recessive disorders are inherited | Recessive disorders occur when an individual inherits two recessive alleles; affected individuals are often born to heterozygous parents who are phenotypically normal carriers. |
| incomplete dominance | heterozygotes show blended phenotypes |
| multiple allelism | more than two alleles exist for a gene |
| codominance | both alleles are fully expressed in heterozygotes |
| Pleiotropy | one gene affects multiple traits |
| Polygenic inheritance | multiple genes contribute to one phenotype |
| Explain why human skin coloration is not sufficiently explained by polygenic inheritance | Human skin color is influenced by both multiple genes and environmental factors, making polygenic inheritance alone insufficient to explain the variation. |
| Define the chromosome theory of inheritance | The chromosome theory of inheritance states that genes are located on chromosomes, which segregate and assort independently during meiosis |
| explain the chromosomal basis of the laws of segregation | segregation occurs during anaphase I |
| explain independent assortment | independent assortment results from random orientation in metaphase I |
| Explain how linked genes are inherited differently from nonlinked genes | Linked genes are located close together on the same chromosome and tend to be inherited together unless crossing over occurs during prophase I |
| Explain how sex is genetically determined in humans | Humans use the X–Y system where females are XX and males are XY; the presence of the Y chromosome determines male development. |
| Describe patterns of sex-linked inheritance | Sex-linked genes are located on sex chromosomes, usually the X chromosome, and recessive X-linked traits are more commonly expressed in males because they have only one X chromosome |
| similarities of the structures of DNA and RNA | DNA and RNA are both nucleic acids made of nucleotides. Each nucleotide contains a nitrogenous base, a five-carbon sugar, and a phosphate group. |
| DNA | o Sugar: deoxyribose o Bases: A, T, C, G o Structure: double helix (two strands) DNA contains genetic information |
| RNA | o Sugar: ribose o Bases: A, U, C, G (uracil replaces thymine) o Structure: single strand |
| Explain how the structure of DNA facilitates its replication | the two strands separate and each strand acts as a template for building a new complementary strand. Because of this base pairing, the new DNA molecules are identical to the original |
| helicase (dna replication) | untwists and separates the DNA double helix |
| original strand (dna replication) | Each original strand becomes a template |
| DNA polymerase (dna replication) | adds complementary nucleotides to form new strands |
| leading strand (dna replication) | synthesized continuously |
| lagging strand (dna replication) | synthesized in short fragments |
| DNA ligase (dna replication) | joins the fragments together |
| Result of DNA replication | Two identical DNA molecules, each with one old strand and one new strand. |
| Transcription | Location: Nucleus Reactants: DNA and RNA nucleotides Product: mRNA DNA is copied into mRNA it contains codons that code for a specific amino acids |
| Translation | Location: Cytoplasm (ribosomes) Reactants: mRNA, tRNA, amino acids Product: Polypeptide (protein) ribosomes read these codons and link amino acids together to form a polypeptide chain (protein). |
| codons | three-base sequences |
| polypeptide chain | protein |
| mRNA is produced using DNA | transcription: RNA polymerase binds to the promoter on DNA, DNA unzips, RNA nucleotides pair with the DNA template strand, RNA polymerase joins the nucleotides to form mRNA, Transcription stops when a terminator sequence is reached. |
| how eukaryotic RNA is processed before leaving the nucleus | RNA processing: • Introns (noncoding regions) are removed. • Exons (coding regions) are spliced together. • A cap is added to the beginning. • A tail is added to the end. The processed RNA becomes mature mRNA and leaves the nucleus. |
| Relate the structure of tRNA to its functions in translation | tRNA is a folded molecule with two important parts: • Anticodon • Amino acid attachment site This structure allows tRNA to bring the correct amino acid to the ribosome. |
| Anticodon | base triplet that pairs with the codon on mRNA |
| Amino acid attachment site | carries a specific amino acid |
| Describe the structure of ribosomes. | made of rRNA and Proteins, large subunit, small subunit, binding sites of mRNA and tRNA |
| Describe the function of ribosomes. | Hold mRNA and tRNA together, joins amino acids to form a growing polypeptide chain. |
Created by:
Lworzalla123